How do I relocate my base in War Commander?

Then choose one of the friends listed to relocate to their sector, or hit the "Random" button to go to a random sector.

A pop-up message will ask you to confirm, letting you know that all your platoons will be returned to your base. Any bookmarks you have will be reset, and you'll also lose control of all Resource Deposits. If you're sure, hit the "Relocate My Base" button.

There is a chance that the sector you want to move to is full. If this is the case, a pop-up message will tell you so and let you know that you can try to relocate again to another sector.

How often can I relocate?

As the above screenshot shows, you are able to relocate once for free every 7 days. This timer can be reset with the use of in-game gold.